The mechanism of the tape medium noise is investigated by comparing the mag
netization fluctuation resulting fro mi an incremental dc erase process. It
is found that the produced magnetization fluctuation displays contrasting
behavior for recording heads with two very different gap lengths. A quantit
ative analysis of the medium noise mechanisms indicates that the sensitivit
y of the record head to spacing fluctuations explains these differences, an
d it is concluded that the main mechanism of the medium noise in advanced t
ape media is the head medium spacing fluctuation due to surface roughness.